BioStar has proposed a rapid assay for measuring collagenase activity in gingival crevicular fluid (GCF) to diagnose periodontal disease, which is very prevalent in the U.S. population, affecting up to 75% of adults. Most diagnostic techniques available to clinicians cannot predict future attachment loss. Collagenase in CGF is an important marker of disease activity, but previous methods have been unsuitable for clinical use. A variation of BioStar's proprietary OIA technology will be developed for direct physical detection of collagenase activity. This technology exploits the optical properties of thin films of biomolecules on a patented testpiece; as thickness decreases due to enzymatic digestion, a color change occurs. Results will be available in minutes. Ease of use and low cost make it suitable for office use. Results will be semiquantitative, differentiating between health, gingivitis, and active periodontitis. The specific aims of Phase I are to determine the best method for immobilizing collagen on the testpiece so pure collagenase can measurably degrade it, and to determine the conditions that allow differentiation of clinically relevant enzyme levels. The prototype developed in Phase I will be evaluated and modified during clinical studies in Phase II development.